Automated method for cutting tissue retainers on a suture

ABSTRACT

An automated method for manufacturing self-retaining suture is disclosed. The suture is mounted to a support. A power-operated cutting arm moves a cutting device through the suture along a preselected path and at a preselected angle to create a tissue retainer having a desired shape and size. The suture is indexed relative to the cutting device. The operation of the cutting arm in conjunction with the geometry of the cutting device and linear advancement of the suture thread allows for creating a plurality of tissue-retainers having a desired geometry along the length of the suture thread.

CLAIM TO PRIORITY

This application is a continuation of U.S. application Ser. No.11/691,845, filed on Mar. 27, 2007, now pending; which is a continuationof U.S. application Ser. No. 10/486,123, filed Jul. 2, 2004, now U.S.Pat. No. 7,225,512, issued Jun. 5, 2007; which claims priority under 35USC §371 to PCT/US2002/027525, filed on Aug. 29, 2002, published on Mar.6, 2003 under Publication No. WO03/017850A1, now expired; and is acontinuation-in-part of U.S. application Ser. No. 09/943,733, filed Aug.31, 2001, now U.S. Pat. No. 6,848,152, issued Feb. 1, 2005. All of theabove claimed priority applications are incorporated herein by referencein their entireties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a method of barbing suture filament by varyingthe blade geometry and/or the movement of a blade when cutting a suturefilament where the method can also be utilized to cut a plurality ofaxially spaced barbs on the exterior of sutures and an apparatus forperforming this.

2. Description of the Prior Art

In the prior art, it is well known that surgical and traumatic woundsare typically closed with a filament introduced into the tissue by aneedle attached to one end. Closure of the wound and holding tissuestogether supports healing and re-growth. What is typically used for thisprocedure is known as a suture.

A barbed suture is a one-way suture which allows passage of aneedle-drawn suture in one direction through tissue, but not in theopposite direction. A barbed suture is generally an elongated bodyhaving a pointed leading end and a plurality of axially andcircumferentially spaced barbs on the exterior surface of the elongatedbody.

In closing a wound with a barbed suture, the suture is passed throughtissue at each of the opposed sides of a wound. Suture pairs are formedin which trailing ends of sutures are positioned generally in alignmentat opposite sides of the wound. On insertion of each suture, the needleis pushed to extend out of the tissue at a point laterally remote fromthe wound, then the needle is pulled out to draw the suture to thedesired position, and the suture is then severed from the needle. (Notethat methods of using barbed sutures are disclosed in copending U.S.patent application Ser. No. 09/896,455, filed Jun. 29, 2001, entitled“Suture Method” and assigned to Quill Medical, Inc., the disclosure ofwhich is incorporated herein by reference.) The advantage of usingbarbed sutures is that there is an ability to put tension in the tissuewith the result of less slippage of the suture in the wound. The numberof suture pairs is selected in accordance with the size of the wound andthe strength required to hold the wound closed. Although tissueanchoring is easier done with a very pointed barb and a relativelyskinny tip, better tissue holding results are obtained with a fuller tipbarb.

In some circumstances of tissue repair, a random configuration of barbson the exterior of the suture might be preferred. With as many barbangles as possible, superior wound holding would be achieved. However,in other circumstances where the wound or tissue repair needed is small,a small suture would be preferable. A small suture would require areduced number of barbs on the exterior of the suture. Various methodsof cutting the barbs have been proposed (see e.g. U.S. Pat. No.5,931,855). However, such methods have not been commercially exploitedfor reasons which are unclear.

It is seen from the foregoing that there is a need for a method ofcutting barbs on the exterior of sutures with a minimum of difficultyand in a reliable and relatively economic fashion so as to allow for thewide spread commercialization of such sutures. Such a method should alsobe able to vary the size of the barbs, their location and depth to allowfor variation thereof and versatility of their application. The methodshould be able to cut a plurality of barbs with the positioningdepending on the number of barbs needed. The need also exists for adevice able to use the method described above which can provide aplurality of axially spaced barbs either in a random or similarconfiguration, with the configuration depending upon, among otherthings, the type of tissue being repaired.

SUMMARY OF THE INVENTION

It is therefore a principal object of the present invention to providefor a practical method of cutting barbs in a suture.

It is therefore a further object of the present invention to provide amethod for cutting fuller tipped barbs of various sizes on the exteriorof a suture.

It is therefore a still further object of the present invention toprovide a method for cutting a plurality of axially spaced barbs on theexterior of a suture.

It is therefore a still further object of the present invention toprovide a method for cutting a plurality of axially spaced barbscircumferentially about the exterior of a suture.

It is therefore a still further object of the present invention toprovide a method for cutting a plurality of axially spaced barbs insimilar or random configurations on the exterior of a suture.

It is therefore a yet further object of the invention to provide for anillustrative apparatus to perform this method.

To attain the objects described, there is provided a cutting methodwhich produces suture barbs of varying sizes depending on the geometryof the blade being used and/or the movement of the blade when cuttinginto a suture. By altering the blade geometry and/or degree ortrajectory of blade movement, the barbs can be made of varying sizesdesigned for various surgical applications. For example: for joining fatand relatively soft tissues, larger barbs are desired, whereas smallerbarbs are more suited for collagen intensive tissues. Also, the use of acombination of large and small barbs on the same suture will ensuremaximum anchoring properties wherein barb sizes are customized for eachtissue layer.

The cutting method may be achieved with a cutting device disclosedherein. The device disclosed can produce six sets of barbs in staggeredpositions along the length of a suture, such that three sets of barbsare faced opposite to another three sets of barbs. Viewing the suture ona cross-sectional plane, the barb sets would be positioned either 120 or180 degrees to each other, depending on the cutting method.Longitudinally, each barb cut would begin where the nearest one ends.

Compared with the method of cutting barbs in an untwisted state, usingthe twisted configuration can simplify production equipment; produce astronger suture; reduce production cycle time by at least a factor ofthree; and be easily scalable to smaller diameters and produce barbs ina spiral fashion rather than at 120 or 180 degrees.

By way of variations, slight modifications, and/or combinations of themethods of cutting with and without twisting the suture, barbs can beobtained with random configurations. There are instances in tissuerepair that the random configuration may be ideal to anchor tissues inas many barb angles as possible to provide superior wound holdingproperties. These and other objects and characteristics of the presentinvention will become apparent from the further disclosure to be made inthe detailed description given below.

BRIEF DESCRIPTION OF THE DRAWINGS

Thus by the present invention its objects and advantages will berealized the description of which should be taken in conjunction withthe drawings wherein

FIGS. 1A-F depict the cutting motion of a blade with one degree offreedom from movement and two degrees of freedom from blade geometry.

FIGS. 2A-C depict the cutting motion of a blade with two degrees offreedom from blade movement and one degree of freedom from bladegeometry.

FIGS. 3A-C depict they cutting motion of a blade with three degrees offreedom from blade movement and a solid plane geometry.

FIGS. 4A-C depict a zigzag (oscillating back and forth and downward)cutting motion of a blade with three degrees of freedom from blademovement and solid plane blade geometry.

FIGS. 5A-C depict the cutting motion of an articulating blade with threedegrees of freedom from blade movement.

FIG. 6 is a top view of the assembled cutting device.

FIG. 7 is a perspective view of the cutting bed.

FIG. 8 depicts an end, a side, and a cross-sectional view of theretention knob of the cutting device.

FIG. 9 depicts a top and side view of the blade assembly of the cuttingdevice and a top view of an example blade for the blade assembly.

FIG. 10 depicts a top and side view of the template block of the bladeassembly.

FIG. 11 depicts a top and side view of the cutting template used withthe cutting device.

FIGS. 12A-B depict a top and side view of the tamp used with the cuttingdevice.

FIG. 13 depicts the securing of the suture to the retention knob andplacement on the spacing bar.

FIG. 14 depicts the placement of the various fixtures used with thecutting bed vise.

FIG. 15 depicts the blade assembly placement and downward movement inrelation to the cutting template with the rest of the cutting deviceremoved from the figure for clarity purposes.

FIG. 16 depicts the blade assembly placement and upward movement inrelation to the cutting template.

FIGS. 17A-F are front views depicting the setting of barbs in thecutting bed vise before and after cutting using the 120 degree rotationmethod of cutting.

FIGS. 18A-B are front views depicting the setting of the suture in thecutting bed vise before cut using the twisting method of cutting.

FIGS. 19A-D depict the various conditions of a suture before and afterthe twisting method of cutting.

FIG. 20 is a side, top and detail view of a barbed suture using the 120degree rotation method of cutting.

FIGS. 21A-C depict perspective views of a linear indexing mechanism witha rotary reciprocating blade assembly.

FIG. 22 is a perspective view of a rotational indexing mechanism with arotary reciprocating blade assembly.

DETAILED DESCRIPTION OF CERTAIN PREFERRED EMBODIMENTS

We refer now to the drawings in detail wherein like numerals refer tolike elements throughout the several views.

The purpose of the present invention is to provide for an effective wayof producing a barbed suture. In this regard, several different types ofmethods are disclosed which are directed to the cutting action of ablade on the suture to create the barbs. As will be described, thecutting action envisioned takes into account the movement of the bladeand the blade geometry.

Essentially, the cutting of the suture with a blade takes into accountthree dimensions x-y-z of the suture 6. Each dimension is important andmay be addressed by the cutting motion of the blade and/or the bladegeometry. Depending on the blade geometry, the blade movement can havean effect in the other dimensions.

In this regard, FIG. 1A illustrates a consistent cutting motion of ablade 8 with one degree of freedom of movement and two degrees offreedom from blade geometry across a suture 6. One degree of freedomfrom movement is movement in one direction in a three-dimensional“x-y-z” layout. For FIG. 1A, direction 2 follows the lateral “x” axis inthe cut of suture 6, with the movement of blade 8 in direction 2 beforeaccomplishing a cut. An edge 10 of blade 8 has an angle, depicted as 12,in its blade geometry between the tips of sides 14, 16 of blade 8, aswell as an angle (not shown) in its blade geometry between the top andbottom planes of blade 8. Such a geometry will cause an effect in the yand z dimensions (i.e. in the length and depth of the barb) just by themovement of blade 8 in the x direction.

As shown in FIG. 1B, these angles allow a cut into suture 6 in the y andz directions during movement in direction 2. This cutting-into movementis depicted as resultant direction 18. FIG. 1C depicts the completed cutof suture 6 with a continued movement in direction 2 away from thesuture 6.

Similar to FIG. 1A, FIG. 1D illustrates a cutting motion of a blade 8with one degree of freedom of movement and two degrees of freedom fromblade geometry across a suture 6. In FIG. 1D, blade 8 is a hollow groundblade, in which edge 10 has an angle in its blade geometry between thetips of its sides 14, 16, as well as a concave or curved-in face in itsblade geometry between the top and bottom planes of blade 8. Such ageometry will cause an effect in the y and z dimensions (i.e. in thelength and depth of the barb) just by the movement of blade 8 in the xdirection.

As shown in FIGS. 1E and 1F, this blade geometry allow a cut into suture6 in the y and z directions during movement of blade 8 in direction 2.Comparison of FIG. 1E with FIG. 1F illustrates how movement of blade 8in direction 2 increases the length and depth of the barb.

Turning now to FIGS. 2A-C, a consistent cutting motion of a blade withtwo degrees of freedom of movement and one degree of freedom from bladegeometry is illustrated. Two degrees of freedom of movement is movementin two directions x and y. For FIG. 2A, direction 2 follows the lateral“x” axis and direction 22 follows the forward “y” axis in the cut ofsuture 6. In this regard the movement of blade 8 in two directions 2 and22 simultaneously may be used to accomplish a cut. Edge 10 of blade 8 isat an angle of 90° or less, depicted as 24, of one degree in its bladegeometry between the tips of sides 14, 16 of blade 8.

As shown in FIG. 2B, forward movement in direction 22 and along alateral direction 2 allows a longer cut into suture 6 than produced inFIG. 1, since in FIG. 1 the blade geometry and blade movement in thex-axis determines the length of the barb, whereas in FIG. 2 the bladegeometry and blade movement along both the “y” and “x” axes determinesthe length of the barb. This longer cutting action is in the “y”direction. FIG. 2C shows the completed cut of the suture 6 with acontinued movement in direction 2 away from the suture.

FIG. 3A illustrates a further consistent cutting motion of a blade withthree degrees of freedom of blade movement and edge 10 of 90° or less.Three degrees of freedom from movement is movement in the threedirections of a three-dimensional “x-y-z” layout. For FIG. 3A, direction2 follows the lateral “x” axis, direction 22 follows the forward “y”axis and direction 32 follows the downward “z” axis. The movement ofblade 8 in all three directions 2, 22 and 32 may be used to accomplishthe cutting of a barb on the suture 6.

The combination of movement in lateral direction 2, forward direction 22and downward direction 32 would allow one to vary the length and depthof the cut to create a barb. It may be a deeper barb by cutting furtherin direction 32 and/or a longer barb by cutting further in direction 22.By moving blade 8 in lateral direction 2, forward direction 22 anddownward direction 32 simultaneously forms a trajectory, which may bealtered to create barbs with different qualities such as aspect ratios.FIG. 3C shows the completed cut of suture 6 with a continued movement indirections 2, 22, and 32 away from the suture 6.

A yet further method of cutting a barb is shown in FIGS. 4A-C where aback and forth or zigzag (oscillating on the “x” axis combined with themovement in z and/or y axis) motion of the blade with three degrees offreedom of blade movement and a solid plane geometry cuts the barb witha saw-like cutting motion. Three degrees of freedom of movement ismovement in three directions in the three-dimensional “x-y-z” layout. InFIG. 4A, direction 2 follows the lateral “x” axis, direction 22 followsthe forward “y” axis, direction 32 follows the downward “z” axis, anddirection 42 follows the lateral “x” axis except in a direction oppositeto direction 2. FIG. 4A shows the movement which may be used toaccomplish a cut of blade 8 in directions 22 and 32 with alternation inmovement between directions 2 and 42. Edge 10 of blade 8 would bestraight between the tips of sides 14, 16 of blade 8.

The combination of alternating movement in lateral directions 2 and 42,steady movement in forward direction 22 and steady movement in downwarddirection 32 allows the depth of the cut to be varied. The resultantzigzag cutting motion is shown as alternating direction 44 in FIG. 4B.FIG. 4C shows the completed cut of suture 6.

A still further method of cutting a barb is shown in FIGS. 5A-5C wherearticulation of blade 8 about an axis 9, in combination with any of thecutting motions described in FIG. 14 above, may be used to vary thedepth of the barb. In FIG. 5A, direction 2 follows the lateral “x” axis(into the plane of the drawing), direction 22 follows the forward “y”axis and direction 32 follows the downward “z” axis. FIG. 5B shows theblade movement which may be used to accomplishing a cut of blade 8 indirections 2 and 22, similar to that depicted in FIG. 2B. Forwardmovement in direction 22 and along a lateral direction 2 produces a barbbased on two degrees of freedom of blade movement. In FIG. 5C, blade 8is also allowed to articulate about axis 9, providing an additionaldegree of freedom, which may be used to impart additional barb depth indirection 32 in the z-axis. This articulating motion of blade 8 may beemployed in combination with any of the blade geometries and/or blademovements previously described. Articulation of blade 9 may also be usedto lift a cut barb up and away from the surface of suture 6, therebyleading to a fuller or more pronounced barb.

The blade motion shown in FIGS. 1-5 can cut a suture filament made ofpolyglycolide, polydioxinone, polypropylene, other resorbables, othernonresorbables, Gore-Tex®, bi-component material or sutures made ofother material suitable for the purpose.

While in the aforesaid examples, only a single blade is shown, it isenvisioned that a plurality of blades may be utilized. They may be intandem or on a rotary mechanism or on any other type of mechanicaldevice which effects the implementation of the movement so described.Also, while the suture is shown in an untwisted state, it may be cut ina twisted state as hereinafter described.

By way of examples of mechanical devices for implementing the foregoing,reference is made to FIGS. 6-19 and 21-22. It should be understood,however, that these devices should not be considered exclusive and othertypes of devices for such implementation are contemplated.

Turning now more particularly to FIG. 6, there is shown a cutting device50 that allows an operator to cut multiple barbs on the exterior ofsuture 6 using the methods previously described. The cutting device 50includes retention knobs 52, 54 for retaining the suture 6 on a vise 63during cutting. Retention knobs 52, 54 include knob holders 61, 62.Cutting bed vise screws 58, 60 are used to open and to close cutting bedvise 63, where suture 6 is placed during cutting.

A cutting template 64 directs the cutting motion of a blade assembly 66containing a plurality of blades across suture 6. Two additional cuttingtemplates are provided for operation of the cutting device but areoffset to provide a different axial position of the blades with respectto suture 6. The cutting templates have the same configuration ascutting template 64 and are installed in a similar manner throughout theseveral views. Also, while the templates shown are particularly suitedfor practicing one way of cutting the barbs, such templates can bereadily modified to allow the performance of other ways, including thosepreviously described as will be appreciated by a skilled artisan.

Cutting bed vise 63 assists in the alignment of the cutting templates.On the top of block 68 of cutting bed vise 63 are two protrusions. Theseprotrusions are alignment pins 70, 72 which are used for setting thecutting templates and a tamp 101.

As will be apparent to one skilled in the art, the configuration ofcutting bed vise 63 may vary. If the suture is rotated (e.g. 120 degreesor 180 degrees) to effect cutting barbs about its circumference, thecutting bed vise may be configured as shown in FIG. 6. If the suture istwisted prior to cutting, as will be discussed, the cutting bed vise 63preferably has a configuration with trapezoidal sides such as thoseshown in FIG. 7. Because suture material is somewhat compliant, thisdesign provides superior clamping to a vise with parallel sides. Notethat the vise shown in FIG. 7 can also be used with a rotated suture,since there is a space to accommodate a cut barb. In this regard, inFIG. 7, blocks 68, 74 taper outward from the tops on their interiorsides to a surface 76, with the blocks depicting a trapezoidal shapewhen viewed from an end profile. Protruding from the taper of block 68is a trapezoidal or anvil suture clamp 78 which is used to secure suture6 during the closing of cutting bed vise 63. Suture clamp 78 is a wedgeshape which sets on surface 76 and ends slightly below top 80.

In addition to securing suture 6, retention knobs 52, 54 are rotatedbetween the various cutting methods and are numerically indexed forprecise movement. As depicted in FIG. 8, retention knob 52 is a solidelongated body. Retention knob 52 comprises a cylinder 82 having agripping area 84 integral with a triangular protrusion 86. Triangularprotrusion 86 can rest on cutting bed 56 or a spacing bar 100, shown inFIG. 13. An anchor screw 90 secures suture 6 to the retention knob. Thetriangular protrusion includes numerical marks for guiding the operatorin positioning the retention knob during various stages of the cuttingmethod; however, the triangular protrusion may be indexed in othervariations. One side of the triangular protrusion has the number “1”imprinted, another side has the number “2” imprinted and a third sidehas the number “3” imprinted. Retention knob 54 has the samecharacteristics as retention knob 52.

For cutting a plurality of barbed sutures at one time, a multi-bladeassembly is used. As depicted in FIG. 9, blade assembly 66 consists of aplurality of blades 8 secured in retaining block 92. In FIG. 8, thirteenblades are depicted, although obviously the number of blades used mayvary. Edge 10 of each of the blades used in the blade assembly 66 wouldextend through a template block 94, shown in FIG. 10 by the amount ofthe desired barb depth.

Retaining block 92 of FIG. 9 consists of two rectangular blocks whichretain blade assembly 66 by a vise action. Blade assembly 66conformingly fits to a cutaway section of the retaining block and blades8 are inserted at a desired angle, which in this case is 148 degrees.The blades are secured in the retaining block 92 with the template block94 attached thereto. Template block 94 acts as a guide for the bladeassembly within the confines of the cutting templates.

As shown in FIG. 11, the cutting template 64 provides a cutting path 97for blade assembly 66. Cutting path 97 is shown as a parallelogramperimeter. Note, however, for example, the cutting path 97 may be shapedwith a rectangular perimeter to suit the movements described in thecutting method of FIG. 1, or other shapes to permit additional degreesof blade movement as described in FIGS. 2-5. Additional cuttingtemplates are provided and are similarly made with the purpose ofoffsetting the blade cut in an axial direction. The cutting template 64is identified so as to indicate to the user which one is to be used atwhich stage of cutting. On opposite sides of the cutting template 64 isa channel 99 sized to accommodate the other sections of suture 6 notbeing cut by blade assembly 66.

As shown in FIG. 12A, a tamp 101 is provided to insure that suture 6 isuniformly seated on the anvil 78. Apertures 102, 104 on tamp 101 areprovided to engage the alignment pins 70, 72. A channel 105 is providedto hold suture 6 in place during the calibration. The depth of thechannel 105 equals the thickness of the suture 6 above vise top 80.

To operate cutting device 50, first one secures the suture 6 to anchorscrews 90 on one of retention knobs 52, 54 as shown in FIG. 13.Retention knob 52 is placed on the ledge of spacing bar 100 with thesuture 6 drawn there-across with the second retention knob 54 positionedon the opposing ledge. The suture should not be overly taut once it issecured to the second retention knob by anchor screw 90. After sizing,suture 6 is placed on cutting bed 56 and held in place by cutting bedvise 63. The retention knobs 52 and 54 are indexed in a first position.As will be apparent in a second and third cutting for a barbed suturehaving barbs spaced 120 degrees apart, retention knobs 52 and 54 arerotated to second and third positions respectively.

As shown in FIG. 14, the tamp 101 is placed on the cutting bed 56positioning the suture 6 in vice 63 which is tightened, and the tamp isthen removed. Cutting template 64 is then placed onto cutting bed 56.

In the cutting method of suture 6, blade assembly 66 is placed ontocutting bed 56. The blade assembly is pressed down while slid from thetop of the cutting template to the bottom along path 97 as shown in FIG.15. The blade depth is set to produce the desired depth of the barb.After blade assembly 66 stops at the bottom of cutting template 64, theblade assembly is removed. To create barbs in a direction opposite thosefirst cut, blade assembly 66 may then be turned 180 degrees and placedonto cutting bed 56 as shown in FIG. 16. The left and top of the bladeassembly are in contact with the right and bottom of the cuttingtemplate along path 97. The blade assembly is pressed down while theblade assembly is slid from the bottom to the top. After the bladeassembly 66 stops at the top of cutting template 64, the blade assemblyand the template are removed.

As the process proceeds, suture 6 may be rotated, e.g. 120 degrees, 180degrees, etc., and the cutting process repeated as shown in FIGS. 15-16.The suture should be set securely in the opening of cutting bed vise 63and previously cut barbs should not project above top surface 80, andthe process is repeated. For three sets of barbs about thecircumference, the suture is rotated three times, for two sets, twotimes, etc.

FIG. 17A-F shows the setting of the barbs in vise 63 before and aftercutting for a suture having barbs spaced 120 degrees apart. FIG. 17Ashows the vise open, suture 6 uncut, with vise notches 120, 122 unused.FIG. 17B shows the vise closed with blade assembly 66 about to cutsuture 6. FIG. 17C shows the vise opened after the first set of barbsare cut and placed in notch 122. FIG. 17D shows the vise closed beforeblade assembly 66 engages suture 6 to cut the second set of barbs. FIG.17E shows the vise open with two sets of barbs shown and placed innotches 120, 122. FIG. 17F shows the vise closed before blade assembly66 engages suture element 6 for the cut. After cutting, the suture 6 isremoved and examined. As will be apparent to a skilled artisan,additional or fewer notches may be provided for protecting barbs duringsubsequent cutting steps.

In the twisting method of cutting barbs, suture 6 is set up aspreviously described and twisted along its axis. The number of twistsrequired is dependant upon the number of barbs, the material of thesuture and the diameter of the suture. For example, it has been foundthat size 0, PDS-2 material requiring 2½″ of barbs would requiretwisting it thirty-nine times for an acceptable result. Of course, toomuch twisting may cause the suture material to overrun itself, leadingto undesirable results including damaged suture material.

The securing of a twisted suture 6 on cutting bed 56 is, however,slightly different. In this regard, FIGS. 18A and B show the setting ofsuture 6 in clamp 76 before and during cut. FIG. 18A shows suture 6being placed in the vise prior to clamping, with FIG. 18B showing thesuture post clamping. The lightly clamped suture 6 forms an ellipticalshape and is ready to be cut. The cutting method of suture 6 would bethe same as that afore-discussed without, however, the need for thesuture to be rotated.

FIGS. 19A-D show the various conditions of suture 6 using the twistingmethod of cutting. In FIG. 19A the suture 6 is shown unmodified, with animaginary line 150 shown to depict its longitudinal axis. FIG. 19B showsthe suture 6 as it is twisted in direction 152 in preparation forcutting. FIG. 19C shows barbs cut in the twisted condition, with barbscut along one side thereof. After the suture 6 has been cut and allowedto return to its untwisted condition, the barbs are such as those shownin FIG. 19D where the barbs spiral around the circumference of thesuture.

The difference in the placement of the barbs in the twisted versus theuntwisted method can best be seen by comparing FIG. 19D with FIG. 20. InFIG. 20, the suture 6 cut in the untwisted state is shown with spacedbarbs at 120° about the circumference of the suture 6. In FIG. 19D, thesuture 6 was cut in the twisted state, and, upon de-twisting, thepattern of the barbs takes on a spiral configuration along the length ofthe suture 6.

Note that by omitting cutting motions when suture 6 is cut in either atwisted or untwisted state, the barbs can be formed in a randomconfiguration on the exterior of the suture. Also, the suture may be cutin both a twisted and untwisted state to produce other types of randomconfigurations of barbs.

Alternate embodiments for cutting barbs according to the presentinvention are shown in FIGS. 21-22. FIGS. 21A-C show a linear indexingmechanism for advancing suture 6 along cutting bed vise 63 in direction22, while reciprocating blade assembly 250 cuts barbs along the axis ofsuture 6. Suture 6 may be advanced along cutting bed vise 63 in atwisted state to form spiral cut barbs as shown in FIGS. 21A and B, inan untwisted state, or rotated about its axis in increments (e.g. 120degrees, 180 degrees, etc.) as it advances as shown in FIG. 21C.

Reciprocating blade assembly 250 includes blade 8 connected via arm 225to a linear reciprocating solenoid 220, which reciprocates in direction2 and 42 corresponding to the x-axis, and to rotary solenoid 230, whichcan turn about its axis as shown in FIGS. 21A and B. Cutting bed vise 63is synchronized with reciprocating blade assembly 250 and the indexingmechanism such that the vise closes to hold suture 6 in place duringcutting and opens to allow suture 6 to be advanced by the indexer to thenext cutting position.

Linear solenoid 220 and rotary solenoid 230 may be adjusted to controlthe linear stroke and blade angle of arm 225 of reciprocating bladeassembly 250 to allow for varying the depth of the barbs cut in the yand z axes. In addition, rotation of rotary solenoid 230 allows barbs tobe cut in the opposite direction along the axis of suture 6 as shown inFIG. 21B. The blade angle and stroke may also be adjusted to seversuture 6 at any desired length.

FIG. 22 shows a rotational indexing mechanism for advancing suture 6. InFIG. 22, suture 6 is shown advancing around a rotating drum 210, whilereciprocating blade assembly 250 cuts barbs along the axis of suture 6.Suture 6 is fed onto drum 210 and into cutting channel 215 via suturesupply spool 300. Barbed suture is wound off drum 210 onto take-up spool310. Spools 300 and 310 may supply and take up suture 6 in an untwistedstate, or alternatively, either or both spools may be rotated in such away as to twist and untwist suture 6 to allow spiral cut barbs asdescribed above.

While the invention has been described in connection with what isconsidered to be the most practical and preferred embodiment, it shouldbe understood that this invention is not to be limited to the disclosedembodiment, but on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

1. A method for cutting barbs on a suture thread having a longitudinal axis, the method comprising: (a) setting the suture thread on a support; (b) actuating an electrically-operated reciprocating blade assembly to create a first barb at a first location on the suture thread; (c) indexing the suture thread along the longitudinal axis; and (d) actuating the electrically-operated reciprocating blade assembly to create a second barb at a second location on the suture thread longitudinally-displaced from the first location.
 2. The method of claim 1, further comprising repeating steps (c) and (d) a plurality of times to create a plurality of barbs at a plurality of locations.
 3. The method of claim 1, wherein step (c) comprises: (c1) indexing the suture thread along the longitudinal axis; and (c2) rotating the suture thread around the longitudinal axis.
 4. The method of claim 1, wherein step (c) comprises: (c1) indexing the suture thread along the longitudinal axis; and (c2) rotating the suture thread by 120 degrees around the longitudinal axis.
 5. The method of claim 1, wherein step (b) comprises: actuating an electrically-operated reciprocating blade assembly by actuating at least one solenoid to move a blade through the suture thread to create a first barb at a first location on the suture thread.
 6. The method of claim 1, wherein step (b) comprises: actuating an electrically-operated reciprocating blade assembly by actuating at least one solenoid to change a blade angle of the blade relative to the suture to create a first barb at a first location on the suture thread.
 7. The method of claim 1, wherein the support has an open configuration for moving the suture thread and a closed configuration for stabilizing the suture thread and wherein: step (b) comprises placing the support in the closed configuration and then operating a reciprocating blade assembly to create a first barb at a first location on the suture thread; and step (c) comprises placing the support in the open configuration and then indexing the suture thread along the longitudinal axis.
 8. The method of claim 1, wherein the support has a channel and step (a) comprises setting the suture thread on a support with a portion of said suture thread in the channel of the support.
 9. A method for cutting a suture thread having a longitudinal axis, the method comprising: (a) setting the suture thread on a support; (b) operating a power-operated blade assembly to make a first angled cut having a preselected configuration at a first location on the suture thread; (c) indexing the suture thread along the longitudinal axis; and (d) operating the power-operated blade assembly to make a second angled cut having said preselected configuration at a second location on the suture thread longitudinally-displaced from the first location.
 10. The method of claim 9, further comprising repeating steps (c) and (d) a plurality of times to make a plurality of angled cuts said preselected configuration at a plurality of locations.
 11. The method of claim 9, wherein step (c) comprises: (c1) indexing the suture thread along the longitudinal axis; and (c2) rotating the suture thread around the longitudinal axis.
 12. The method of claim 9, wherein step (c) comprises: (c1) indexing the suture thread along the longitudinal axis; and (c2) rotating the suture thread by 120 degrees around the longitudinal axis.
 13. The method of claim 9, wherein step (b) comprises: operating the power-operated blade assembly by actuating at least one solenoid to make a first angled cut having a preselected configuration at a first location on the suture thread.
 14. The method of claim 9, wherein step (b) comprises: operating the power-operated blade assembly by actuating at least one solenoid to change a blade angle of the blade relative to the suture and make a first angled cut having a preselected configuration at a first location on the suture thread.
 15. The method of claim 9, wherein step (c) comprises indexing the suture thread along the longitudinal axis utilizing a first spool to feed suture and a second spool to take-up suture thread.
 16. The method of claim 9, wherein the support has an open configuration for moving the suture thread and a closed configuration for stabilizing the suture thread and wherein: step (b) comprises placing the support in the closed configuration and then operating the power-operated blade assembly to make a first angled cut having a preselected configuration at a first location on the suture thread; and step (c) comprises placing the support in the open configuration and then indexing the suture thread along the longitudinal axis.
 17. The method of claim 9, wherein the support has a channel and step (a) comprises setting the suture thread on a support with a portion of said suture thread in the channel of the support.
 18. A method for creating tissue-retainers on a suture thread having a longitudinal axis, the method comprising: (a) setting the suture thread on a support; (b) operating a power-operated cutting assembly to cut the suture thread to make a first tissue-retainer having a preselected configuration at a first location on the suture thread; (c) indexing the suture thread along the longitudinal axis; and (d) operating the power-operated cutting assembly to cut the suture thread to make a second tissue-retainer having said preselected configuration at a second location on the suture thread longitudinally-displaced from the first location.
 19. The method of claim 18, further comprising repeating steps (c) and (d) a plurality of times to make a plurality of tissue-retainers having said preselected configuration at a plurality of locations.
 20. The method of claim 18, wherein the support has an open configuration for moving the suture thread and a closed configuration for stabilizing the suture thread and wherein: step (b) comprises placing the support in the closed configuration and then operating a power-operated cutting assembly to cut the suture thread to make a first tissue-retainer having a preselected configuration at a first location on the suture thread; and step (c) comprises placing the support in the open configuration and then indexing the suture thread along the longitudinal axis. 